1. What Is a Press Brake Die?

A press brake die is the lower forming tool that supports the sheet while the upper punch applies force.

The die opening and geometry determine how the sheet flows during bending and strongly influence final radius, required tonnage, minimum flange, and surface contact.

2. Press Brake Punch vs Die

The punch is the upper tool and the die is the lower tool.

3. Main Parts of a V-Die

• V-opening: width of the lower opening.
• Die shoulders: support the sheet during bending.
• Die angle: included angle of the V cavity.
• Shoulder radius: affects marking and material flow.
• Die height: affects machine setup and daylight.
• Base / mounting surface: interfaces with the press brake table or die holder.

4. Main Types of Press Brake Dies

The most common categories are:

• Single-V dies
• Multi-V dies
• 4-way dies
• Acute dies
• Hemming / flattening dies
• Offset / Z-bend dies
• Radius / forming dies
• Rotary or mark-free dies
• U-dies and channel dies
• Custom dies

5. Single-V Die

A single-V die contains one V-opening and is optimized for a specific range of material thicknesses and bending conditions.

Advantages include high rigidity, simple setup, precise geometry, and strong load capacity.

Single-V dies are ideal for repeat production where the same opening is used frequently.

6. Multi-V Die

A Multi-V die provides several openings in one tool body.

Operators can rotate or reposition the die to select the most suitable opening.

This reduces tool-change time and is especially useful in job shops.

Read our Multi-V Die Guide.

7. 4-Way Press Brake Die

A 4-way die is a common type of Multi-V die with one opening on each side of the tool body.

Different V widths can be selected by rotating the die.

Because each side has different geometry and remaining cross-section, load ratings can vary between openings.

8. Acute Die

An acute die has an included angle significantly below 90° and is used with acute punches.

Typical applications include:

• Acute-angle bending
• Springback compensation
• Overbending
• Hemming preparation

Read our Acute Punch Guide.

9. Hemming / Flattening Die

A hemming or flattening die is used after a flange has been pre-bent to an acute angle.

The second operation flattens or partially closes the flange.

It can produce open hems, closed hems, and teardrop hems.

Read our Press Brake Hemming Tool Guide.

10. Offset / Z-Bend Die

Offset dies are paired with matching offset punches to create two opposing bends, often in one stroke.

They are used for Z-bends, joggles, step bends, and overlapping panel features.

Read our Press Brake Offset Tool Guide.

11. Radius / Forming Die

Radius dies are designed for larger curved profiles or special forming operations.

They may be used with a large radius punch or custom upper tool.

Read our Radius Punch Guide.

12. Rotary / Mark-Free Die

A rotary die uses moving or rotating elements to support the sheet during bending.

This can reduce sliding friction and surface marking compared with conventional fixed V-die shoulders.

Rotary dies are useful for cosmetic stainless, aluminum, coated panels, and other surfaces where appearance is critical.

13. U-Die and Channel Die

U-dies and channel dies form U-shaped or channel-shaped profiles.

They are useful for repetitive parts where two side walls must be formed to a controlled width and depth.

Tool geometry must provide enough release clearance for the finished part.

14. Custom Press Brake Dies

Custom dies are designed around a specific part profile that cannot be formed efficiently with standard tooling.

Common custom applications include:

• Special channels
• Complex offsets
• Large radii
• Special hinges
• Embossing
• Custom ribs
• Special architectural profiles

15. How to Choose the Right V-Opening

V-opening selection affects nearly every important bending result.

For common thin mild-steel air bending, a V-opening around six to eight times material thickness is often used as a practical starting range.

This is not a universal rule.

16. V-Opening vs Material Thickness

These are only starting examples for ordinary air bending. Always verify the actual material, target radius, flange length, tonnage, and tooling recommendations.

17. How V-Opening Affects Bend Radius

In air bending, a larger V-opening normally produces a larger natural inside radius.

A smaller V-opening normally produces a tighter radius.

This is why changing dies can change the finished radius even when the same punch is used.

Read our Press Brake Radius Guide.

18. V-Opening and Minimum Flange Length

The flange must remain supported by the die shoulders during bending.

A larger V-opening requires a longer minimum flange.

If the flange is too short, it can fall into the opening or become unstable during forming.

19. V-Opening and Press Brake Tonnage

A larger V-opening reduces required bending force.

A smaller V-opening increases bending force.

Use our Press Brake Tonnage Calculator before production.

20. Common Press Brake Die Angles

• 30°
• 45°
• 60°
• 85°
• 88°
• 90°

Acute dies allow overbending and springback compensation, while near-90° dies are common for standard bending.

21. Die Shoulder Radius

The shoulder radius is the radius where the sheet contacts the top edges of the V-opening.

It affects friction, marking, surface quality, and material flow.

A larger, smoother shoulder radius can reduce marking on sensitive sheet.

22. Press Brake Die Materials

Common tooling materials include 42CrMo, SKD11, and Cr12MoV.

42CrMo offers a strong toughness-to-cost balance, while SKD11 and Cr12MoV provide higher wear resistance for suitable applications.

Read our Press Brake Tooling Materials Guide.

23. Heat Treatment and Hardness

Die performance depends heavily on heat treatment.

The working surfaces must resist wear while the tool body retains enough toughness to withstand bending loads.

Ask the supplier for material grade, hardness, heat-treatment method, hardness depth where applicable, and rated load.

24. Press Brake Dies for Mild Steel

Mild steel is relatively easy to form and works well with standard single-V or Multi-V dies.

Choose the opening based on thickness, target radius, flange length, and tonnage.

25. Press Brake Dies for Stainless Steel

Stainless steel usually requires more force and exhibits more springback than mild steel.

A larger V-opening may help reduce tonnage, but it also increases radius and minimum flange length.

Surface marking should be considered for cosmetic parts.

26. Press Brake Dies for Aluminum

Aluminum can mark easily and some alloys can crack if bent too tightly.

Use suitable V-openings, smooth shoulder radii, and protective films or low-mark tooling where needed.

27. Dies for High-Strength Steel

High-strength steel normally requires larger V-openings, larger minimum radii, and higher-capacity tooling.

Always check the steel manufacturer’s forming recommendations and the die load rating.

28. Press Brake Dies for Air Bending

Air bending is the most common modern press brake process.

The sheet contacts the punch and die shoulders but does not fully conform to the die cavity.

V-opening strongly influences natural radius and tonnage.

29. Press Brake Dies for Bottom Bending

Bottom bending drives the sheet deeper into the die and uses more direct tooling contact.

Tool angle and geometry become more important, and required force is higher than air bending.

30. Press Brake Dies for Coining

Coining uses very high localized pressure to force the sheet into the tooling geometry.

Only use dies specifically designed and rated for the required load.

Read our Air Bending vs Bottom Bending vs Coining Guide.

31. Press Brake Die Selection Chart

32. How to Judge Press Brake Die Quality

• Accurate V-opening
• Consistent die angle
• Accurate shoulder radius
• Straightness
• Verified material certificate
• Controlled heat treatment
• Good surface finish
• Rated load documentation
• Correct mounting dimensions

33. Common Press Brake Die Selection Mistakes

• Using one V-opening for every thickness.
• Choosing the smallest V-opening without checking tonnage.
• Choosing a large V-opening without checking flange length.
• Ignoring how V-opening changes bend radius.
• Ignoring surface marking on cosmetic parts.
• Using an acute punch with an incompatible die angle.
• Assuming every Multi-V opening has the same load capacity.
• Using standard tooling for high-force coining without approval.
• Changing dies without updating bend deduction or springback corrections.

34. Press Brake Die Maintenance and Storage

• Keep V-openings and shoulders clean.
• Remove scale and metal particles.
• Inspect shoulders for wear and chipping.
• Protect mounting and reference surfaces.
• Apply rust protection during long storage.
• Store heavy dies securely.
• Do not drop hardened tooling.
• Remove cracked or overloaded dies from service.

35. Frequently Asked Questions About Press Brake Dies

What is a press brake die?

It is the lower forming tool used with a punch to bend sheet metal.

What is a V-die?

It is a die with a V-shaped opening used for press brake bending.

What is a single-V die?

It is a lower die with one V-opening.

What is a Multi-V die?

It is a die with multiple V-openings in one tool body.

What is a 4-way die?

It is a Multi-V die with four selectable sides or openings.

What is an acute die?

It is a die with an included angle below 90°, used for acute bending and overbending.

What is a hemming die?

It is tooling used to flatten or partially close a pre-bent flange.

What is an offset die?

It is a special die used with a matching punch to create Z-bends, joggles, or step bends.

What is a rotary die?

It is a die with moving elements designed to reduce friction and surface marking.

How do I choose a V-opening?

Choose based on material thickness, target radius, minimum flange, tonnage, surface requirements, and tooling capacity.

What V-opening should I use for 2 mm steel?

V12–V16 is a common starting range for normal mild-steel air bending, subject to part requirements.

Does a larger V-opening reduce tonnage?

Yes.

Does a smaller V-opening increase tonnage?

Yes.

Does V-opening affect bend radius?

Yes. In air bending, it strongly influences the natural inside radius.

Does V-opening affect minimum flange?

Yes. Larger openings require longer minimum flanges.

Can I use the same die for stainless and mild steel?

Sometimes, but stainless normally requires more force and may need a different opening for optimal results.

Can I bend aluminum with a standard V-die?

Yes, but consider minimum bend radius and surface marking.

Which die is best for cosmetic sheet?

Rotary, low-mark, polished, or protected tooling can help reduce surface damage.

What die is best for hemming?

An acute die for pre-bending followed by a flattening or hemming die.

What die is best for Z-bending?

A dedicated offset die is best for one-hit Z-bends and joggles.

What material is best for press brake dies?

42CrMo is common for general use, while SKD11 and Cr12MoV may be used for higher wear resistance.

How do I check die load capacity?

Use the tooling manufacturer’s rated tonnage per meter for the exact die and opening.

Can I coin with a Multi-V die?

Only if the manufacturer explicitly rates that opening for the very high coining load.

Can Delem store die geometry?

Yes. Suitable Delem controls can store die dimensions in the tooling library.

Why does changing the die change my flat pattern?

The V-opening can change actual bend radius and therefore bend allowance and bend deduction.

What information should I send when ordering a die?

Send press brake model, lower-tool mounting style, material, thickness range, bend length, target radius, minimum flange, punch type, and typical part drawings.

36. Related YRS Industrial Guides

• Press Brake Tooling Guide
• Press Brake Tooling Materials Guide
• Multi-V Die Guide
• Gooseneck Punch Guide
• Acute Punch Guide
• Radius Punch Guide
• Press Brake Hemming Tool Guide
• Press Brake Offset Tool Guide
• Press Brake Radius Guide
• Springback in Sheet Metal Bending Guide
• Bend Allowance vs Bend Deduction
• Air Bending vs Bottom Bending vs Coining
• Press Brake Tonnage Calculator
• Sheet Metal Bending Guide
• Press Brake Programming Guide
• Delem CNC Controller Knowledge Center

37. Need Help Choosing a Press Brake Die?

YRS Industrial supplies CNC press brakes and press brake tooling for sheet metal fabrication. We can recommend single-V dies, Multi-V dies, acute dies, hemming dies, offset dies, radius dies, and custom tooling according to your material, thickness, part geometry, and machine.

For a tooling recommendation, send your press brake model, lower-tool mounting photo, material grade, thickness range, maximum bend length, target inside radius, minimum flange, punch type, typical part drawings, and production volume.

Technical Note

Press brake die selection depends on material grade, actual thickness, target radius, minimum flange, V-opening, bend angle, surface requirements, active bend length, tool geometry, and rated load. The common 6–8 × thickness guideline is only a starting point for many mild-steel air-bending applications and should not replace actual tooling calculations or manufacturer recommendations.